“Who the blazes is that?” Paul asked.

The male intruder said, as though it was supposed to mean something, “That is Rustum Battachariya.” The amplified voice continued, “If there is a way for Sebastian Birch to gain access to a ship, he must be stopped. Under no circumstances can he be allowed to leave Ganymede.”

“There are hundreds of ships up there on the surface,” Paul said. “A whole fleet of them. Hell, surface access here is right next to a major spaceport.”

“And Sebastian is an expert pilot — a natural, according to the man who gave us lessons.” Jan spoke to the ceiling again. “Surveillance. Priority report. What are Sebastian Birch’s present actions and location?”

“Sebastian Birch is moving across the surface at seven kilometers an hour. He is now in Sector eighty-four.”

“The spaceport sector.” As Paul said those words. Jan shivered. She asked, “Surveillance, how close is he to a ship?”

“Forty-seven ships in operating condition lie within four hundred meters of his present location.”

“Do they have crews aboard?”

“That information is not available.”

Paul said, “Chances are, none of them will have a crew aboard,” as the voice came again from the wrist unit. “Sebastian Birch must be stopped, by whatever method. He must not be permitted access to a ship able to leave the surface of Ganymede.”

Jan challenged. “Why not? What makes you think you can give orders?”

“At the moment it would be counterproductive to tell you my reasons for concern. Let me say only that this issue is of paramount importance, and could lead to… many deaths. If you question my credibility, ask Magrit Knudsen of the Coordinators’ Office about Rustum Battachariya — but, I beg you, do it later.”

Jan made a hard decision. She knew that Sebastian was completely harmless, but — “Paul, we have to stop him.”

He, thank God, did not question her. He said at once, “Surveillance, couple to spaceport operations. Operations, this is Paul Marr, first officer of the OSL Achilles. We have warning of a potential escapee from quarantine. Any individual found on the surface in Sector eighty-three should be taken into custody and held pending my arrival. Use whatever means are necessary to secure him.”

Jan thought, And break my heart. She swallowed and said to Paul, “I have to go after him. Myself. I have to.”

“I know. I’m coming with you.”

The man, Alex Ligon, said, “What about us?”

Paul stared at him for a moment. “Look, I don’t know what you’re doing here, or who you are. But I have pilot rating for everything from a one-person hopper to the biggest liners. If you can beat that for space credentials, come along. Otherwise, don’t bother and don’t get in the way.”

The man scowled and opened his mouth, but it was the woman, Milly Wu, who got in first. “You tell us to look, now you look. We’ve had no sleep for close to a full day. I can’t speak for Alex Ligon, but I’ve had only half a meal since breakfast yesterday. We came running over here because we were told that somebody might be in trouble. We don’t know your friend Sebastian Birch, and we don’t know why he has to stay on Ganymede. But as for me, I’d be just as happy never to meet him. Here.” She took the wrist unit and tossed it to Jan. “Take it or leave it. If you want to know anything else, don’t ask me. Ask Bat.”

Jan cut off a developing argument. “Paul, I know your credentials very well and they don’t need to. We have no time for a fight. You two, go back to Battachariya, whoever and wherever he is. Anything needs sorting out about your coming here, we do it later.”

She left before there could be more discussion. Ten seconds later, Paul had caught up with her. “You were right,” he said. “And I was wrong. I’ve found out where my ego lies. They were just caught in the middle. Mind if I lead the way?”

Jan didn’t. Once they were out on the surface, Paul’s lead would be essential. She had been outside before, but compared to him she was a tyro. She fumbled her way into a suit at maximum speed and ran the last twenty meters up the surface ramp.

Looking off to her right as they emerged onto Level Zero she again saw a spiky city of gantries and scaffolds, glittering in reflected sunlight. Their layout had changed since last time. Ships by the dozen — by the hundred — lay scattered at the feet of the construction rigs, everything from bulbous freighters to spindly-legged singletons. High above everything hung the familiar ball of Jupiter, swollen and striated. To Sebastian it might be an object of infinite fascination, but she could imagine how others saw it: only a madman would leave Ganymede and fly closer to Jupiter, just to stare at atmospheric cloud patterns.

Jan heard a crackle on the wrist communications unit, then Milly Wu’s voice. “Rustum Battachariya is still on the line. He wants to keep in touch with you. I’ll try to patch him in to local video and audio.”

The voice that sounded in Jan’s suit, however, was not that of Rustum Battachariya. A musical contralto said, “Janeed Jannex? This is spaceport operations. We are taking over from automated surveillance. We have tracked your man, and he is entering a Mayfly-class single-seater.”

Paul broke in. “This is Paul Marr, first officer of the Achilles. Can you stop him taking off?”

“Oh, hi, Paul. Tess Walkabie here. Prevent him? How?”

Jan said, “Override the ship’s controls.”

“Come on, you ought to know better than that. Manual controls can always override remotes.”

Paul said, “What I had in mind was sending someone out to the ship.”

“Who? We have only three people on duty. Cargo arrivals and departures are automated, and no passenger ships are scheduled. We weren’t expecting emergencies, or much of anything. Don’t you people ever sleep? It’s the middle of the graveyard shift.”

The woman was right. To Jan, it seemed no particular time of day or night. She would do better to leave things to Paul, who knew what he was doing.

The woman went on, “If this Sebastian takes it into his head to fly, he’ll be gone long before we could get there. In fact, you are closer to him than we are.”

“Close enough to reach him in time to stop him taking off?”

“No. But I can direct you to another ship, Paul — a Flyboy scooter, two-person. Lots of volatiles already onboard.”

“That would be perfect. A Flyboy is faster than anything in the Mayfly class. No matter where he goes, we’ll be able to follow and catch him. Is it ready to lift?”

“Ready as you are. Do you want it?”

“Yes!”

“It’s yours. Bear twenty degrees left of your present heading. Keep moving and I’ll steer you to it.”

Jan needed steering. Lack of sleep, her over-rich meal, and the strange surroundings combined to remove her from reality. Her previous experience on the surface of Ganymede had been an unhurried stroll. Now she struggled to keep up with Paul, following him across a gritty plain of water-ice crystals a hundred and fifty degrees below their freezing point. It was not a run. It was not a walk. It was a rapid, unsteady shuffle past looming insectile derricks and through the long black shadows cast by squatty cargo hulls.

A flash of blue on her right made Jan turn that way. “There goes the Mayfly,” said the contralto voice. “He’s away. Don’t worry, you have less than a hundred meters to go.”

Neither Paul nor the chief of operations, Tess Walkabie, had said anything about the size of the scooter they would fly. Jan, climbing after Paul up the short ladder, found herself apologizing as she squeezed in beside him. Paul didn’t even acknowledge that he had heard her. He had taken the controls, and was flicking through a lightning status check.

Jan said, “I thought this was supposed to be ready to fly?”

“I’m sure it is. You just don’t skip your own checkout, ever. We’re in good shape. Operations? We’re ready to go, but I don’t have visual contact.”